The aim of this proposal is to develop a series of fluorogenic imaging molecules, which can be easily delivered into viable cells and monitor cellular functions. The FIMs are composed of a peptide backbone containing a target site for a kinase or a protease. Some designs borrow from the molecular beacon approach and carry flurophore/quencher moieties, while other designs simply carry a flurophore only. When present, the quencher moiety is internal to the FIM rather than at the extreme N- and C-terminus, as has been the case with other similar type beacons. This avoids the need for structural constraint, which aims to be imposed in order to bring the flurophore and quencher into close proximity to each other thereby preventing background fluorescence. Specifically, the scope of this proposal will cover the design, synthesis and testing of two peptides containing cleavage sites specific for caspase-1 (ICE) and caspase-3 (CPP32). Also included in this proposal is the design, synthesis and testing of fluorogenic peptides derived from a differentially phosphorylated, essential domain of human cdd25C phosphatase, which is involved in induction of the mitotic process.